Free Revit Viewer?

www.autodesk.de has an extended post on how to view Revit files for free at this link:
Autodesk - Autodesk Revit Viewer Free

The page reviews the following methods (none of which are very exciting):

For Revit files There are various possibilities.

Display native Revit files

• Revit installation in viewing mode

Viewing exported data

• Viewing DWF in Autodesk Design Review
• DWF viewing in Internet Explorer
• DWF Viewing into NavisWorks
• Viewing in NWD NavisWorks Freedom

The English equivalent to the .de page is considerably shorter:
http://usa.autodesk.com/adsk/servlet/ps/dl/item?siteID=123112&id=7290003&linkID=9243099